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Runs only when start switch depressed

J

Jon Stern

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"1990 454 only runs when start

"1990 454 only runs when start switch is depressed. Changed low oil sensor. There must be an open circuit somewhere. I assume when the starter is engaged, all other safety systems ( oil, temp ) are bypassed and when the engine starts the other systems are engaged. Something is open.

Any suggestions on where to start tracking down this electrical problem. Coil, plug wires, distributor and resistor bar are all new. Electric fuel pump is working fine.

That's about all I can think of. Thanks for the help."
 
"I have a 1984 454 CID Crusade

"I have a 1984 454 CID Crusader. There is a switch with a set of contacts that are closed when the transmission is in the neutral position and open when in the forward or reverse positions. This switch prevents the starter from energizing unless the transmission is in the neutral position. I don’t think this switch is responsible for your symptoms. There is an oil pressure switch in the ignition circuit. When there is low oil pressure the switch is open and prevents the engine from running if the oil pressure is lost. When the starter solenoid is energized, the oil pressure switch is bypassed.

If the engine dies after the starter switch is released, it could be an indication that the oil pressure switch is faulty or disconnected, the oil pressure is low or the starter switch is faulty. I would put a manual pressure gage on the engine to determine if you have an oil pressure problem. If your oil pressure is ok with this measurement and you have normal oil pressure indicated on the panel, I would expect the oil pressure switch or a loose connection. You can place a temporary jumper across the oil pressure switch to check it. Having said all that, I would bet on the starter switch. You can also place a jumper across the ignition switch to determine if the switch is the problem.

I hope this is helpful.

Chuck Hanson"
 
"Thanks Chuck & Rick

I&

"Thanks Chuck & Rick

I'll check the key switch in the morning. How can I test the solenoid. Although the solenoid and starter were rebuilt less than 2 years ago. But I guess that doesn't make any difference.

I should also mention that this boat is set up with a key switch and a start button. Turn the key on and then press the start button to energize the solenoid and turn the starter.

I am using a remote push button switch connected directly to the solenoid to prevent running up & down to the flybridge. I leave the key switch on the on position while using the remote switch.

I think the key switch is prime suspect right now. I will post the results of the test tomorrow.

Again, thanks for the help.

Jon"
 
"Hey, Jon, here's an easy

"Hey, Jon, here's an easy thing to try: Turn on the key, then look for 12 volts at the coil. If it's not there, that's the problem. If so, work backwards until you find voltage, and there's your problem.

Jeff

PS: Sure is easy for me to say!"
 
"Thanks for the suggestions.

"Thanks for the suggestions.

The problem turned out to be a fault connection to the tranny overheat switch. Fixed that and it started right up.

I have a new problem with the coil and distributor, but I will start a new post with this.

Thanks again

Jon"
 
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